1. Technical Field of the Invention
The present invention relates to a semiconductor analysis apparatus, a semiconductor analysis method and a method for manufacturing a semiconductor device, in which a minute defective location can be accurately determined by using a Raman spectroscopic analysis.
2. Discussion of Related Art
FIG. 2 shows a block diagram of a conventional semiconductor analysis apparatus. The semiconductor analysis apparatus is used for a method for analyzing defects in semiconductor devices using a liquid crystal analysis. The liquid crystal analysis is an analysis method using a polarizing phenomenon of the liquid crystal.
A device to be measured 101 defining an object to be measured is a semiconductor integrated circuit apparatus in a state in which circuits are completed on a semiconductor wafer. To observe the internal state of the semiconductor integrated circuit apparatus to analyze defects therein, liquid crystal is thinly coated on its surface, and the liquid crystal is heated up to about a polarizing temperature. Then, it is placed in a measurement apparatus that is similar to a semiconductor wafer prober, and probes are abutted against bonding pads thereof to achieve electrical connection. Operation voltages and input signals that operate the internal circuits are supplied through the probes from a tester 105 that is composed of a pattern generation circuit 102, an oscillation circuit 103 and a control circuit 104.
A TV camera 106 photographs the entire area of at least one semiconductor integrated circuit or the entire area of circuits to be focused on the surface of the device to be measured 101. To photograph the device to be measured 101, the camera 106 is provided with a lens system that magnifies and photographs the surface of the device.
As well known, the refractive index of liquid crystal is temperature dependent. In the mean time, wirings and elements on the device to be measured generate heat according to currents that circulate therein. Accordingly, the refractive index of liquid crystal coated on the surface changes according to the wirings and elements in which currents circulate, and they appear as a pattern. In other words, an image photographed by the camera has a pattern corresponding to the wiring and element pattern in which current circulates.
A signal of the image photographed by the camera is converted by a data converter 107 into two-digit pattern data and inputted in a computer 108.
The computer 108 is provided with circuit-logic information 109 and layout information 110 being as expected values, examines the circuit logic information according to inputted conditions given by the tester 105, and forms pattern information of the passages and elements in which current should circulate based on the layout information. The pattern information is compared with the actual pattern obtained by the data conversion described above to thereby analyze presence or absence of defects.
In other words, by coating liquid crystal on a wafer and heating the liquid crystal adjacent to a polarizing temperature, and specifying defective locations that generate heat upon circulating current in the semiconductor integrated circuit, a defect analysis is conducted. Defective locations that can be concretely specified by the semiconductor analysis apparatus are those defective potions caused by metal short-circuits and defective locations having a higher resistance than a designed value. These defective locations involve greater heat generation than the normal case. Therefore, they can be specified as defective locations.
In the conventional semiconductor analysis apparatus described above uses liquid crystal that is harmful to the human body, and the liquid crystal is carcinogenic material. In addition, since the polarizing area of liquid crystal spreads widely, it is difficult to narrow down a spot for detecting a defective location to a minute area. This is becoming a greater problem as the miniaturization of the design rule is further progressed. In other words, it is difficult to accurately specify a minute defective location in a semiconductor integrated circuit apparatus that is greatly miniaturized.
On the other hand, there is a hot electron analysis that takes a shorter analyzing time. However, the hot electron analysis can only be applied to objects that accompany light emission of hot electrons, and thus cannot specify defects involving short circuits.
The present invention is made in view of the circumstances described above, and its object is to provide a semiconductor analysis apparatus, a semiconductor analysis method and a method for manufacturing a semiconductor device, in which a minute defective location can be accurately determined.
To solve the problems described above, a semiconductor analysis apparatus in accordance with the present invention is characterized in comprising:
a laser oscillator that emits a Raman laser beam and a pattern taking laser beam for taking a pattern image of an object to be measured;
a stage for mounting an object to be measured onto which the Raman laser beam and the pattern taking laser emitted from the laser oscillator are irradiated;
a Raman spectroscopy apparatus that takes out to spectroscopically separate scattered light from the object to be measured onto which the Raman laser beam is irradiated, and detects Raman spectra obtained;
a camera that receives reflected light from the object to be measured onto which the pattern taking laser beam is irradiated to obtain a pattern image of the object to be measured; and
a computer that combines data of the Raman spectra detected by the Raman spectroscopy apparatus and data of the pattern image obtained by the camera, to thereby judge a temperature of a fine region in the pattern of the object to be measured.
A semiconductor analysis method in accordance with the present invention is characterized in comprising:
setting a semiconductor integrated circuit defining an object to be measured in an operating state;
irradiating a Raman laser beam and a pattern taking laser beam on the object to be measured;
receiving reflected light of the irradiated pattern taking laser beam reflected on the object to be measured by a camera and detecting a pattern image from data of the received light;
spectroscopically separating with a Raman spectroscopy apparatus scattered light of the irradiated Raman laser beam scattered on the object to be measured, and detecting Raman spectra obtained;
combining data of the Raman spectra and data of the pattern image, to thereby judge a temperature of a fine region in the pattern of the object to be measured; and
detecting from the temperature a defective location that generates heat.
By the semiconductor analysis method described above, a defective location is specified by detecting heat that is generated at the defective location by using a Raman spectrum shift. In this type of Raman spectroscopic analysis, Raman spectrum shifts are sensitive to temperatures of an object to be measured. Therefore, it can specify a defective location such as a subtle metal short-circuit defect to a degree that can be barely specified by a scanning electron microscope (SEM), and is capable of analyzing a spot region of up to 0.2 xcexcm. Therefore, a defective area such as a metal short-circuit can be narrowed down to a fine region in a short time. In particular, defective locations can be readily and accurately specified even when miniaturization of the design rule is further advanced.
A method for manufacturing a semiconductor device in accordance with the present invention is characterized in comprising:
a step of preparing an object to be measured; and
a step of analyzing a defective location in the object to be measured,
wherein the step of analyzing comprises:
setting a semiconductor integrated circuit defining the object to be measured in an operating state;
irradiating a Raman laser beam and a pattern taking laser beam on the object to be measured;
receiving reflected light of the irradiated pattern taking laser beam reflected on the object to be measured by a camera and detecting a pattern image from data of the received light;
spectroscopically separating with a Raman spectroscopy apparatus scattered light of the irradiated Raman laser beam scattered on the object to be measured, and detecting Raman spectra obtained;
combining data of the Raman spectra and data of the pattern image, to thereby judge a temperature of a fine region in the pattern of the object to be measured; and
detecting from the temperature a defective location that generates heat.
Also, in the method for manufacturing a semiconductor device in accordance with the present invention, the step of preparing an object to be measured may be the step of preparing a semiconductor wafer in which a semiconductor integrated circuit is formed in a completed state or an IC chip.